Welcome to “Celebrating Great Local Mathematicians”, a collaborative book created by students and teachers from Croatia, Georgia, Moldova, Poland, Portugal, Romania, Serbia, Spain, and Turkey as part of the eTwinning project “Mathematics Is All Around Us.” 

    Mathematics is often described as the universal language — a tool that connects people across time, space, and cultures. Whether it’s geometry, algebra, or calculus, Math has been a common thread shaping human progress. But behind every theorem, equation, and discovery, there are brilliant minds whose stories deserve to be told.

    This booklet is a celebration of those minds, local mathematicians from our countries who made significant contributions to the world of numbers, logic, and problem-solving.

    Let’s celebrate math, our local heroes, and the friendships we’ve built along the way. 

    Happy reading!

    The Mathematics Around Us Team 

            Table of Contents

    The Romanian Genius of Geometry: Gheorghe Țițeica  p. 4

    A man with a thousand faces and occupations: Ruđer Bošković p. 14

   A Genius who merged Mathematics and Physics: Marin Getaldić p. 24

    Al-Biruni p. 30

    Hüseyin Ali Nesin p. 33

    Cahit Arf p. 41

    Halil Vehbi Eralp p. 45

    Gelenbevi Ismail Efendi: A Prominent Turkish Mathematician p. 51

    Hüseyin Tevfik Paşa p. 55

    Kerim Erim p. 57

    Jabir Ibn Hayyan p. 59

    Câbir bin Eflah p. 64

   Abū Nasr Muhammad ibn al-Farakh al-Fārābi p. 66

   Abu Abdullah Muhammad bin Musa al-Khwarizmi p. 70

   Matrakçı Nasuh p. 72

                 The Romanian Genius of Geometry:

                            GHEORGHE ȚIȚEICA

                            Born: October 4, 1873, Drobeta-Turnu Severin, Romania            Died: February 5, 1939, Bucharest, Romania
                            Field: Mathematics – Differential Geometry

Gheorghe Ţiţeica was born on October 4, 1873, in Turnu-Severin. His father, a boiler worker on Danube ships, passed away when Gheorghe was young.

A gifted student, Gheorghe excelled in his studies and earned scholarships to pursue mathematics in Craiova and Bucharest. He graduated the University of Bucharest in 1895 and continued his education in Paris, where he earned a doctorate in 1899.

After returning to Romania, Ţiţeica became a professor at the University of Bucharest, where he taught for nearly 40 years.

Internationally renowned, Gheorghe Ţiţeica made significant contributions to geometry, chaired sessions at global mathematics conferences, and lectured at prestigious universities.

Gheorghe Țițeica specialized in differential geometry, a branch of mathematics that focuses on curves, surfaces, and their properties. His most notable achievement was the creation of the Țițeica Surfaces, a special class of surfaces that bear his name. These surfaces are studied in geometry even today!

In addition to his research, Țițeica made significant contributions to mathematical education. He authored numerous textbooks and scientific papers, helping to train a new generation of mathematicians in Romania. His work ensured that Romania became recognized as a center for mathematical excellence in Europe.

"Mathematics is a way of expressing the laws of nature; it is the simplest and most suitable form to present a general law or the course of a phenomenon. It is the most perfect language in which a natural phenomenon can be described."

                                                              ***

Gheorghe Țițeica’s dedication to mathematics and education serves as an inspiration to all of us. He showed that with hard work, curiosity, and creativity, we can make discoveries that last for generations. His legacy reminds us that math is not just about numbers — it’s about seeing patterns, solving problems, and exploring the beauty of the world.

Țițeica's Challenge

                The Five-Leu Coin Puzzle

Imagine you have a 5-leu coin, and you need to split it into pieces. But here's the challenge:

Can you figure out how to divide the coin?

Solution:

The best way to split the 5-leu coin is into three pieces:

Now, let's check how you can make each amount:

      A man with a thousand faces and occupations:

                 RUĐER BOŠKOVIĆ

                             Born: 18. 5. 1711. in Dubrovnik

                                     Died: 13. 2.1787. in Milano

                                     Fields: Mathematics, Physics, Rhetoric,                                                                   Philosophy, Theology, Astronomy, 

                                                 Archaeology

Literature: https://enciklopedija.hr/clanak/boskovic-rudjer-josip, https://sh.wikipedia.org/wiki/Sferna_trigonometrija and /Ruđer Bošković

Biography of Ruđer Bošković:

- Ruđer Bošković began his education in Dubrovnik at the Collegium Ragusinum, and continued at the Jesuit institute Collegium Romanum in Rome. As a student of theology, he began (1740) to teach mathematics at the Collegium Romanum. He was ordained a priest in 1744 and held the chair of mathematics until 1760.

- He established an exact scientific approach to solving static issues in construction by solving static problems of sacred and cultural buildings.

- Ruđer Bošković deals with the problems of the shape and size of the Earth - he introduced the term spheroid for the shape of the Earth.

- He was a professor of mathematics at the University of Pavia. He founded the Observatory in Brera near Milan (1764). He then took over the astronomy chair in Milan. At the invitation of a friend, he moved to Paris in 1774, received French citizenship and was an official of the Ministry of Foreign Affairs and director of optics at the Ministry of the Navy.

- theory of transformation of geometric places

- construction of spherical trigonometry

- graphical method of solving triangles

- four basic formulas of differential trigonometry

- In the work Fundamentals of all mathematics (Elementorum universae matheseos, 1754), Ruđer presents the theory of transformations of geometric places and the original theory of conic sections based on the synthetic method.

- Spherical trigonometry is the trigonometry of a spherical triangle, i.e. learning about the dependence between the sides and angles of a spherical triangle. Unlike ordinary plane trigonometry, in spherical trigonometry the three angles of a triangle uniquely determine its shape and dimensions.

Quote of Ruđer Bošković:

           Republic of Dubrovnik

Facts and Fun Facts about Ruđer Bošković:

- In 1761, Ruđer Bošković was elected a member of the Royal Society. At the instigation of that society, he went to Constantinople to observe the passage of Venus in front of the Sun. As he did not have time to observe the passage of Venus, he used the time to explore the ruins of Troy. 

- Ruđer Bošković was a member of nine academies, including the academies in Bologna (1746), Paris (1748), Saint Petersburg (1760), and London (1761).

Ruđer's challenge

This forms a spherical right triangle with three right angles (90° each), which is impossible in Euclidean geometry but completely valid in spherical geometry.

        A Genius who merged Mathematics and Physics: 

                            Marin Getaldić

Born: October 2, 1568, Dubrovnik, Republic of Ragusa (modern Croatia)

Died: April 8, 1626, Dubrovnik 

Fields: Mathematics, Physics

Literature: https://en.wikipedia.org/wiki/Marino_Ghetaldi

https://www.dubrovnik-online.net/english/famous_citizens2.php

https://hr.wikipedia.org/wiki/Marin_Getaldi%C4%87

Biography of Marin Getaldić:

     Marin Getaldić started his education in his hometown Dubrovnik. He received his primary education from Franciscans and then finished local Gymnasium. 

    On a year 1597 he started his trip through Europe and following years he lived in Germany, England, France and Italy. During that times he made friendships with many respectable mathematicians, including Francois Viéte and Galileo Galilei. 

    In 1603 he returned in Dubrovnik, wherehe was selected as referee on Appeals court. Till the end of his life he was engaged in politics and was a member of the Great and Small Council of The Republic of Ragusa, the political bodies of the Republic. He was married to Marija Sorkočević Getaldić, who died giving birth to their third daughter.

Contribution to Mathematics:

- developtment of symbolic algebra

- experiments with parabolic mirrors

- His most important work De resolutione et compositione mathematica is completely based on the Viète’s algebraic method. Application of the new method to different problems and theorems of ancient, particularly Euclidean geometry, enabled the reinterpretation of mathematical knowledge and opened the door to new fields of science.

Fun Facts:

- Marin Getaldić caused real awe in his fellow - citizens with his experiments with parabolic mirrors he performed in the cave of St. James, named "Bete`s cave" after his own nickname. The mirrors destroyed metals, lead and silver alike, at a distance. The stories have it that Getaldić put in danger the ships sailing in the vicinity, even putting some of them on fire. One such mirror, two meters in diameter, is displayed at the 

Maritime Museum in Greenwich.

                            Getaldić parapolic mirror, 

                            National Maritime Museum, Greenwich

"Bete's cave", Dubrovnik, Croatia

Quotes of Marin Getaldić:

"Mathematics is the key to understanding nature."

"Nature is guided by laws that can be known by reason."

"Science is not just theorizing, but a tool for solving real problems."